(1) Field of the Invention
The present invention relates to a direct-feed type writing implement.
(2) Description of the Prior Art
Conventional direct-feed type writing implements which use so-called raw ink, i.e., liquid ink are known to employ an ink collector making use of capillary action, e.g., of a vane-like regulator or a fiber bundle for temporal retention of ink, in order to prevent ink leakage due to expansion of the air inside the ink tank accompanying change in ambient conditions such as reduction in pressure and/or increase in temperature.
In a writing implement using the ink collector, in order to positively prevent forward leakage of ink from the writing point side, the size of the ink collector is designed based on the maximum expansion, estimated from the ink tank volume. Therefore, the design of the size of the ink collector depends on the size of the ink tank. That is, the larger the ink tank, the greater the ink collector needs to be.
However, forming a larger ink collector needs more cost. There is another drawback that making the ink collector larger in diameter results in the loss of stylish appearance. Alternatively, if the ink collector is long, the feeder means, such as a center core or the like, which penetrates through the ink collector and leads ink to the writing portion becomes long, so that the long collector configuration produces disadvantages as to forward leakage since the head of ink acts on the writing portion.
In general, it is well known that the ink retention volume of the ink collector is set at 10 to 30% of the ink tank volume. However, there have been demands for the reduction of the size of the ink collector while keeping the ink tank size, or for enlarging the size of the ink tank while keeping the ink collector as is.
As the prior art examples, Japanese Utility Model Publication Hei 4 No. 36293 and Japanese Utility Model Publication Hei 4 No. 45914 are disclosed in which a pipe element is arranged inside the ink tank to prevent ink blow-out to the outside of the writing element due to a temperature rise and reduction in pressure.
In Japanese Utility Model Publication Hei 4 No. 36293, a tubular valve assembly is provided inside the ink tank to discharge air expanded in the ink tank to the outside when a temperature rise or reduction in pressure occurs, to thereby prevent ink blow-out from the writing point. This prior art example is featured in that the ink storage portion is filled with ink less than half-full and is also characterized by having a valve mechanism in that an area inaccessible to ink is created so that there is continuous communication between the surroundings outside the writing point and the air inside the ink storage.
This prior art example first has the drawback in that the ink tank can be filled with ink less than half-full. If the tank is filled more than half-full and ink reaches the rear end opening of the tubular valve assembly, ink will leak as the air inside the ink tank expands due to a temperature rise or reduction in pressure and blow out by the amount corresponding to the air expansion. Therefore, this prior art example has the problem in that the entire ink tank cannot be filled up with ink.
Further, though in common with all the writing implements having a valve mechanism, the writing point has to be pressed against the paper surface or the like during writing, there is a problem that writers with a light touch will face difficulties in writing.
Other than the tube that discharges the expanded air to the outside, the above prior art example further uses extra parts such as a spring enabling the valve to open and close by pressing of the writing point, needing more parts and hence costing more.
Moreover, since in this prior art example, communication between the area inaccessible to ink in the ink storage portion and the ambient space outside the writing point is established continuously, direct application of this prior art example characterized by the tubular valve assembly to a direct-feed type writing implement having an ink collector will cause the forward leakage problem, i.e., the defect of ink leaking from the writing point. That is, this prior art can be applied only to configurations involving a valve.
Next, in Japanese Utility Model Publication Hei 4 No. 45914, a tubular valve assembly is provided to discharge the expanded air due to a reduction in pressure or temperature rise to the outside, and this tubular valve assembly is extended to the bottom of the ink tank. Further, the rear end of the point assembly is connected to the first tubular valve assembly so that pressing the writing point will open the valve of the tubular valve assembly to thereby equalize the pressure inside the ink storage chamber to the atmospheric pressure. However, this prior art example has the problems as follows.
First, as stated above, since the writing point of a valve type has to be pressed against the paper surface or the like during writing, writers with a light touch face difficulties in writing. In this prior art example, two valves need to be opened for writing, so that light-handed writers experience much more difficulty.
Secondarily, this configuration uses two values, needing more parts and costing more, compared to the first prior art example (Japanese Utility Model Publication Hei 4 No. 36293).
There is another problem. That is, under the situation in which a temperature rise or reduction in pressure is occurring, if the first valve element is opened with the writing point put upwards as when writing is performed with its writing point upwards, the ink will be pushed up inside tubular vale assembly due to the pressure inside the ink tank, causing ink leakage from the writing point.
The present invention is to solve the above problems. Particularly, the object of the present invention is to provide a direct-feed type writing implement having an ink tank equal in volume to that of the conventional configuration but using an ink collector smaller than that of the conventional configuration, or to provide a direct-feed type writing implement having a ink collector equal in size to that of the conventional configuration but being able to store a greater amount of ink than the conventional configuration.
It is another object of the present invention to provide a writing implement which is free from the conventional problems with the conventional configurations in that the entire ink tank cannot be filled up with ink, or ink blow-out occurs with its writing point upwards if the ink tank is filled up with ink and allows the entire ink tank to be filled up with ink without any ink leakage from the writing point when the writing point is set upwards as well as when the writing point is set downwards.
It is a further object of the present invention to provide a writing implement free from the problem that a valve type writing implement makes it difficult for light-handed writers to write, by providing a direct-feed type configuration using an ink collector.
Moreover, it is still another object of the present invention to provide a direct-feed type writing implement which solves the forward leakage problem, which would occur if the principle of Japanese Utility Model Publication Hei 4 No. 36293 is directly applied to a writing implement using an ink collector, by introducing a new mechanism.
Finally, the present invention is to provide a writing implement which is free from the cost problem due to more parts needed in a valve type configuration and still can effectively prevent ink leakage.
In order to achieve the above objects, the present invention is configured as follows:
In accordance with the first aspect of the present invention, a direct-feed type writing implement includes:
a point assembly having a writing point at the tip thereof;
an ink tank directly storing a relatively low viscosity ink having a viscosity of 2 to 100 mPaxc2x7S at room temperature;
an ink collector for adjusting the internal pressure in the ink tank by utilizing capillarity;
a feeder means including a center core, for feeding ink from the ink tank to the writing point; and
a duct pipe connecting the ink collector and the ink tank, and is characterized in that ink is supplied to the center core as the ink feeder means only through the duct pipe.
In accordance with the second aspect of the present invention, a direct-feed type writing implement includes:
a point assembly having a writing point at the tip thereof;
an ink tank directly storing a relatively low viscosity ink having a viscosity of 2 to 100 mPaxc2x7S at room temperature;
an ink collector for adjusting the internal pressure in the ink tank by utilizing capillarity;
a feeder means including a center core, for feeding ink from the ink tank to the writing point;
a duct pipe connecting the ink collector and the ink tank; and
a duct pipe ink storage portion provided for the duct pipe, and is characterized in that ink is supplied to the center core as the ink feeder means only through the duct pipe.
In accordance with the third aspect of the present invention, the direct-feed type writing implement having the above second feature is characterized in that the duct pipe ink storage portion provided for the duct pipe is located near the end part of the ink tank.
In accordance with the fourth aspect of the present invention, the direct-feed type writing implement having the above second feature is characterized in that the duct pipe ink storage portion provided for the duct pipe is located close to the interior wall of the ink tank.
In accordance with the fifth aspect of the present invention, the direct-feed type writing implement having the above first or second feature is characterized in that the end part of the duct pipe or the end of the duct pipe ink storage portion is located approximately at the midpoint of the ink tank or closer to the ink tank bottom than the midpoint.
In accordance with the sixth aspect of the present invention, the direct-feed type writing implement having the above first or second feature is characterized in that the ink collector is provided with an ink channel forming an air-liquid exchanger, and the ink feeder portion for leading ink to the ink channel is formed on the ink collector end face on the ink tank side.
In accordance with the seventh aspect of the present invention, the direct-feed type writing implement having the above first or second feature is characterized in that a fine hole is formed in the communication passage for creating communication between the ink collector for adjusting the internal pressure in the ink tank by utilizing capillarity and the ink feeder means including a center core.
In accordance with the eighth aspect of the present invention, the direct-feed type writing implement having the above first or second feature is characterized in that, when the ink surface is above the duct pipe end portion or the end of the duct pipe ink storage portion with the writing point set downwards, the expansion of the air space when the temperature of the ink tank is increased from room temperature to about 50xc2x0 C., is equal to or lower than the ink retention volume of the ink collector.
In accordance with the ninth aspect of the present invention, the direct-feed type writing implement having the above first or second feature is characterized in that, when the ink surface is above the duct pipe end portion or the end of the duct pipe ink storage portion with the writing point set upwards, the expansion of the air space when the temperature of the ink tank is increased from room temperature to about 50xc2x0 C., is equal to or lower than the sum of the ink retention volume of the ink collector and the volume of the clearance formed between the barrel wall and the ink collector.
In accordance with the tenth aspect of the present invention, the direct-feed type writing implement having the above first or second feature is characterized in that, when the duct pipe is formed with the duct pipe ink storage portion and when the duct pipe is formed with the ink storage portion and an ink pool, the total volume including the retention volume of the duct pipe, the duct pipe ink storage portion and the ink pool, is equal to or smaller than the retention volume of the ink collector.
In accordance with the eleventh aspect of the present invention, the direct-feed type writing implement having the above first or second feature is characterized in that the ink tank is charged with ink until almost full.
In accordance with the twelfth aspect of the present invention, the direct-feed type writing implement having the above first feature is characterized in that the end portion of the duct pipe is shaped into a beveled configuration.
In accordance with the thirteenth aspect of the present invention, the direct-feed type writing implement having the above second feature is characterized in that the end portion of the duct pipe and the duct pipe ink storage portion are shaped into a beveled configuration.
In accordance with the fourteenth aspect of the present invention, the direct-feed type writing implement having the above second feature is characterized in that the duct pipe ink storage portion are shaped into a beveled configuration.
In accordance with the fifteenth aspect of the present invention, a direct-feed type writing implement includes:
a point assembly having a writing point at the tip thereof;
an ink tank directly storing a relatively low viscosity ink having a viscosity of 2 to 100 mPaxc2x7S at room temperature;
an ink collector for adjusting the internal pressure in the ink tank by utilizing capillarity;
a feeder means including a center core, for feeding ink from the ink tank to the writing point; and
a duct pipe connecting the ink collector and the ink tank, and is characterized in that the duct pipe has a duct pipe ink storage portion at a position close to the ink tank end and the inner wall of the ink tank, the end of the duct pipe ink storage portion is located approximately at the midpoint of the ink tank or closer to the ink tank bottom than the midpoint, and ink is supplied to the center core as the ink feeder means only through the duct pipe.